There are two formulations of BoNT-A available: Botox®/Vistabel®, Allergan and Dysport®/Azzalure®, Ipsen - Galderma. These formulations behave distinctly in different ways electrophysiologically and clinically and results obtained with one formulation cannot be extrapolated to the other. There are only few clinical research directly comparing the two formulations in the treatment of forehead lines.